The present disclosure relates to an organic EL display device and an electronic apparatus.
As one example of flat (flat-panel) display devices, there is a display device using, as light emitting sections (light emitting elements) for pixels, current-driven electro-optical elements having light-emission luminances that vary in accordance with the values of currents flowing through the elements. As the current-driven electro-optical elements, organic EL (electroluminescent) elements that utilize electroluminescence of organic material are available. The organic EL elements utilize the phenomenon of emitting light when an electric field is applied to an organic thin film.
A typical organic EL display device using the organic EL elements as light emitting sections for the pixels has the following features. The organic EL elements can be driven with a voltage of 10 V or less and thus are low in power consumption. Since the organic EL elements are self-light-emitting elements, visibility of an image is high compared to a liquid-crystal display device. Furthermore, since the organic EL elements do not employ a lighting component, such as a backlight, reductions in weight and thickness can be easily achieved. In addition, since the response speed of the organic EL elements is quite high, typically, on the order of several microseconds, no afterimage appears during display of a moving image.
Organic EL display devices can employ a simple (passive) matrix system or an active matrix system as its drive system, as in the liquid-crystal display devices. For the active matrix display device, since the electro-optical elements continuously emit light throughout one display-frame period, it is easy to achieve a large-sized, high-definition display device, compared to the simple matrix display device.
The active matrix organic EL display device uses active elements (e.g., insulated-gate field effect transistors) provided in the organic EL elements to control current flowing in the EL elements. As the insulated-gate field effect transistors, TFTs (thin film transistors) are used in general. That is, drive circuits (pixel circuit) for the organic EL elements provided for the pixels are configured using TFTs.
More specifically, the drive circuit of each pixel includes a write transistor for writing a signal voltage of a video signal, a storage capacitor for storing the signal voltage written by the write transistor, and a drive transistor for driving an organic EL element in response to the voltage stored by the storage capacitor (see, e.g., Japanese Unexamined Patent Application Publication No. 2007-310311). In order to compensate for a shortage of capacitance components of the organic EL element, an auxiliary capacitor may be provided for each pixel (see, e.g., Japanese Unexamined Patent Application Publication No. 2009-047764). In addition, depending on the configuration of a pixel circuit, there are also cases in which the number of transistors and capacitance elements further increase (see, e.g., Japanese Unexamined Patent Application Publication No. 2006-133542).